Given, Specific gravity of oil = 0.9 Density of oil, ρ = 0.9 × density of water =0.9×1000=900 kg/m3 This is solved by using Pascal’s Law, which states that pressure at all the points in a horizontal direction will be same. Pressure due to oil height = pressure due water height (ρgh)oil=(ρgh)water 900×9.81×40=1000×9.81×h ∴ h = 36 m of water column